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Butadienyl Diiron Complexes: Nonplanar Metalla‐Aromatics Involving σ‐Type Orbital Overlap
Author(s) -
Yu Chao,
Zhong Mingdong,
Zhang Yongliang,
Wei Junnian,
Ma Wangyang,
Zhang WenXiong,
Ye Shengfa,
Xi Zhenfeng
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202008986
Subject(s) - aromaticity , delocalized electron , chemistry , atomic orbital , ligand (biochemistry) , molecular orbital , crystallography , conjugated system , computational chemistry , electron , molecule , organic chemistry , physics , biochemistry , receptor , polymer , quantum mechanics
A new class of nonplanar metalla‐aromatics, diiron complexes bridged by a 1,3‐butadienyl dianionic ligand, were synthesized in high yields from dilithio reagents and two equivalents of FeBr 2 . The complexes consist of two antiferromagnetically coupled high‐spin Fe II centers, as revealed by magnetometry, Mössbauer spectroscopy, and DFT calculations. Furthermore, experimental (X‐ray structural analysis) and theoretical analyses (NICS, ICSS, AICD, MOs) suggest that the complexes are aromatic. Remarkably, this nonplanar metalla‐aromaticity is achieved by an uncommon σ‐type overlap between the ligand p and metal d orbitals, in sharp contrast to the intensively studied planar aromatic systems featuring delocalized π‐type bonding. Specifically, the σ‐type interaction between the two Fe 3d xz orbitals and the butadienyl π orbital results in the formation of a six‐electron conjugated system and hence enables the aromatic character.